Imidosulphonic Acid, NH(SO3H)2

Imidosulphonic Acid, NH(SO3H)2, the amide of which has already been described, may be obtained as the ammonium salt by mixing sulphuric anhydride vapour with excess of gaseous ammonia and fusing the condensed flocculent product in an atmosphere of ammonia:

3NH3 + 2SO3 = NH(SO3.NH4)2.

The potassium salt may be obtained by heating potassium nitrilosulphonate with water:

N(SO3K)3 + H2O = NH(SO3K)2 + KHSO4.

The lead salt, on decomposition with hydrogen sulphide, yields the free acid.

The salts of this acid may either be neutral, of the type NH(SO3R)2, or "basic," corresponding to NR(SO3R)2. The basic salts are more soluble in water than the neutral salts.